In a copending application Ser. No. 096,606 (filed Nov. 21, 1979; Inventor, A. C. Bouchard), there is described a new and unique photoflash lamp which includes a loose powder, flash-producing composition therein. As described therein, the composition includes a powdered metal and powdered oxidizer in combined form. A preferred powdered metal is zirconium (having a particle size ranging from about 10 to 150 microns) and the preferred oxidizer may be potassium chlorate, potassium perchlorate, or sodium chlorate (with a particle size ranging, e.g., from about 10 to 150 microns). The composition, when ignited, produces a flash of light of sufficient intensity to meet the illumination requirements of today's higher speed films, e.g., ASA 400. One particular advantage of the above lamp is its relatively small size. In Ser. No. 096,606, the lamp possesses an internal volume of approximately 1.0 cubic centimeter or less. The lamp thus readily lends itself to miniaturization, a feature highly desired in the photoflash industry.
Utilization of a flash-producing composition in loose powder form in a photoflash lamp such as the one disclosed in Ser. No. 096,606 has proven advantageous for the following reasons: (1) loose powder compositions require less activation energy for ignition in comparison to similar compositions in a compressed or lacquer-bound (binder) orientation within the envelope; (2) the combustion rate for loose powder composition is faster due to enhanced oxygen diffusion into the fuel matrix; and (3) the inflammation period, that being the time required to transfer energy from the ignition primer mass (if employed) to the composition, is less when using a loose powder composition due to the greater porosity thereof. In addition to the above, use of a binder as an integral part of the composition may prove disadvantageous because typical binder materials emit gaseous products during the lamp's ignition cycle which in turn can attenuate light output and adversely affect envelope containment.
It can be understood from the foregoing that localization of the flash-producing composition within the lamp's envelope is critical to the successful operation of the lamp. Heretofore, localization was accomplished by using the aforedefined binder material, e.g., nitrocellulose, polyvinyl alcohol, etc., which functioned as an adhesive to secure the composition where desired. Unfortunately, however, these materials caused the problems described above (light attenuation, poor containment) when the composition was ignited.
It is believed, therefore, that a photoflash lamp which utilizes a loose powder, flash-producing composition and which provides for positive localization of the composition without the need for a binder or similar materials would constitute a significant advancement in the art.